Travel-size Secret Decoder activity and story book with clues to find and a case to solve;Includes 18 mystery game activity pages, decoder lens, and magic-reveal pen;Special Seek & Find Lens and Spy Pen are easy to use and a valuable addition to any great detective's tool kit;Crack the codes and complete the puzzles and games to solve individual mysteries and the whole case;Helps teach cognitive development and problem solving, and encourages independent play